# 2569
Earlier this week there was a concern that the H5N1 virus outbreak among vaccinated poultry in Hong Kong signaled a `mutation' in the virus, rendering the old vaccine ineffective.
Today, Hong Kong authorities have announced that the newly sequenced virus `did not contain obvious differences from previous viruses'.
That isn't to say that there were zero changes, of course. Single strand RNA viruses are notorious for making errors during replication. Viruses are constantly changing, although most of these `mutations' are evolutionary dead-ends.
We are left, however, with a mystery. If the virus hasn't `changed' significantly, why did the H5N2 vaccine fail?
We are only told that more research is needed.
This report from the Hong Kong Standard.
Dead chickens get H5N1 mutation all-clear
Adele Wong
Friday, December 19, 2008
The H5N1 virus found in dead chickens in a Yuen Long farm had not mutated, Undersecretary for Food and Health Gabriel Leung told the Legislative Council's panel on food safety and environmental hygiene yesterday.
The genetic sequencing of the bird flu virus detected in the farm on December 9 did not contain obvious differences from previous viruses, Leung told the panel.
Leung also said more tests were needed to find out how the chickens contracted the virus.
There was also good news for the public - live chickens can be sold again as early as December 30 if things go smoothly.
The early end to the normal 21-day no-chicken ban means the birds will once again be on the menu for Lunar New Year family festivities.
Meanwhile, an Agriculture Fisheries and Conservation Department spokeswoman yesterday explained why the government has been using an H5N2 vaccine manufactured in the Netherlands to protect local chickens from the flu since 2003, even though recent outbreaks showed the virus strain to be subtype H5N1. She said when vaccines were first introduced to local chicken farms, tests had shown the H5N2 vaccine to be effective against the viruses found in South China.
"The H5N2 vaccine is also effective against H5N1 viruses," the spokeswoman said, adding that in 2006, the government had let US authorities test the vaccine, which also showed it is effective for use in southern China.
"However, no vaccine is 100 percent effective. The government has set up an investigation group on avian influenza to look into the matter," she said.
